1. Technical Field
The present disclosure refers to the technical field of digital signal processing and, in particular, it pertains to an apparatus and method for processing digital images.
2. Description of the Related Art
It is felt that there is a need to improve the quality of a digital image and, in particular, to reduce or eliminate the effects of degradation of the quality of the image due to the presence of color artifacts.
A first type of color artifact is represented by so-called false colors. These are artifacts essentially introduced into the digital image by the interpolation or demosaicing process, suitable for obtaining a digital image in RGB format from a digital image in CFA format.
A second type of color artifact is represented by so-called purple fringing. These are artifacts introduced into the digital image essentially for optical reasons, and in particular they are essentially, but not exclusively, due to the chromatic aberration of the lens of the digital image acquisition device, like for example a camera.
Most image processing techniques of the state of the art aimed at correcting, i.e., reducing or eliminating, color artifacts of the first type indicated above, i.e., false colors, carry out a blurring of the chrominance planes because the problem of false colors is essentially down to incorrect interpolation of the chrominance planes. The aforementioned approach of the state of the art does, however, have the drawback of not distinguishing the false colors from genuine chrominance details, for which reasons it also introduces an undesired color loss of the colored sharp edges.
On the other hand, as regards color artifacts of the second type indicated above, i.e., purple fringing, some of the correction techniques belonging to the state of the art are based on identifying the areas of the image affected by such a defect and on desaturation of them executed on the chrominance planes. U.S. Pat. No. 7,529,405 describes a method aimed at correcting color artifacts and, more specifically, purple fringing, and avoiding excessive reduction of the saturation.